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Abstract

Full left heart bypass reduces the oxygen utilization of the heart to about half the control levels, as measured by coronary sinus flow and arteriovenous oxygen differences. All measured lesser degrees of bypass reduce the oxygen utilization less markedly, but with high statistical significance of the reductions below controls. The reduction in oxygen utilization upon institution of partial or complete left bypass is usually the result more of a decrease in arteriovenous oxygen difference than of a decrease in coronary sinus blood flow. These results support the thesis that left heart bypass should be beneficial in reducing the internal work of the left ventricle in acute left heart failure with competent aortic valve.